1. Field of the Invention
The present invention relates to an input device having an input panel to which data can be inputted by means of input units such as pen-shaped writing instruments or fingertips and a chassis receiving the input panel.
2. Description of the Related Art
Recently, input panels such as touch panels or tablets to which data can be inputted by means of input units such as pen-shaped writing instrument or fingertips approaching or contacting thereto have been widely used as data input units in electronic apparatuses such as PDAs (Personal Digital Assistants) or game machines.
As a method of detecting coordinate information so as to input data to the input panel, there have been known various methods of various types including a resistor film type, an electromagnetic induction type, an electrostatic type, an ultrasonic type, and an optical type. FIG. 7 is a schematic sectional view illustrating an example of a known input device having a resistor film type input panel. As shown in FIG. 7, a pair of detection bases 28 and 29 is opposed to each other in an input panel 24 with a predetermined gap. In the inner surfaces of the detection bases 28 and 29 which are opposed to each other, a plurality of resistor films 30a and 30b are formed by a resistor film made of a light-transmitting material. In addition, when a predetermined portion of the first base 28 disposed on the input side of the input panel 24 is pressed by a writing instrument (not shown), the first detection base 28 is bent so that the resistor film 30a of the first detection base 28 comes in contact with the resistor film 30b of the second detection base 29 disposed on the anti-input side. The input panel 24 detects coordinate information of the contact point on the basis of a resistance ratio between the resistor film 30a and the resistor film 30b at the contact point, and data based on the coordinate information is inputted to the input device.
An input device 23 having the input panel 24 includes a chassis 21 for receiving the input panel 24. The chassis 21 includes a side portion 25 opposed to the side surfaces of the input panel 24, a top wall 22 opposed to an outer peripheral edge of the top surface of the input side to press the top surface of the input panel 24, and a supporting portion 31 opposed to a bottom surface of the anti-input side to support the input panel 24. The chassis 21 receives the input panel 24 in its inner space (see JP-A-2003-157150 for reference).
With the recent trend toward small and thin electronic apparatuses such as game machines having the above-mentioned input device 23, the input device 23 itself is requested to have small thickness. Accordingly, for example, as shown in FIG. 8, it has been tried to realize the small-thickness of the input device 23 by eliminating the top wall 22 of the chassis 21.
However, when the input panel 24 is received in the chassis 21 not having the top wall 22, there is a possibility that foreign materials 27 such as dust or moisture enters into a gap between a side surface of the input panel 24 and the side portion 25 of the chassis 21. In such a case, for example, moisture may enter into the inside of the input panel 24 together with foreign materials entering into the gap between the input panel 24 and the chassis 21. For this reason, the input panel 24 may have a short circuit between the resistor film 30a and the resistor film 30b. As a result, malfunctioning of the input panel 24 may be caused.